Anodizing metal articles



March 27, 1956 E. BERNSTIEL ANODIZING METAL ARTICLES 2 Sheets-Sheet 1Filed Feb. 17, 1953 Inventor m jERA s T/EL A ttorney March 27, 1956BERNSTIEL ANODIZING METAL ARTICLES 2 Sheets-Sheet 2 Filed Feb. 17, 1953Inventor Erwin 36k: TIE!- A ttorney 2,739,931 ANODIZING METAL ARTICLESErwin Bernstiel, Cardiff, Wales, assignor to Rhondda Plating WorksLimited, Dinas, Rhondda, Glamorgan,

Great Britain, a British company Application February 17, 1953, SerialNo. 337,393 Claims priority, application Great Britain February 26, 195217 (Zlaims. (Cl. 204-23) The present invention relates to methods of andmeans T fOI anodizing metal articles, for example fastener ele- .mentsof slide fasteners, made of a suitable metal or :metal alloy, such asaluminium or aluminium alloy. The term metal article as hereinafter usedshall mean an :article which is, at least in part, made of an anodizable.metal, and similarly the term fastener elements shall :mean suchelements made of an anodizable metal.

It is known to anodize fastener elements of slide fastenersafter thefastener elements have been attached to a carrier tape which comprisesan electrically conducting wire at its edge carrying the fastenerelements so that the .fastener elements contact the wire and are, thus,electrically interconnected by the wire.

In modern mass production of slide fasteners, the fastener elements areusually attached to carrier tapes of a considerable arbitrary length andspaced along the tape in groups separated one from the next by a lengthof the tape free from fastener elements, the fastener elements ofcorresponding groups of two such tapes being interlocked with eachother, the tapes being subsequently cut about half way between adjacentgroups of fastener elements whereby to obtain pairs of interlocked slidefastener stringers which are finally provided with a slider and-with endmembers to constitute a complete slide fastener. To anodize the fastenerelements it is desirable to effect the anodizing, while the fastenerelements of the two tapes are interlocked with each other and before thetapes are cut, by passing the tapes through a suitable anodic bath of anelectrolytic cell.

However, various difficulties have been experienced.

The wire at the edge of each tape has to be thin so as not unduly todecrease the flexibility of the slide fastener. Such a thin Wire cannotreliably carry a heavy electric current and, more specifically, cannotreliably carry the current across aggregate lengths of thetapes freefrom fastener elements between successive groups thereof which may beimmersed simultaneously in the electrolytic bath at a given moment.Moreover, the oxide layer formed on the fastener elements duringanodizing is a bad electric conductor, which renders it impossible or atleast difficult, after the oxidization of the surfaces of the slidefastener elements has been initiated, to establish reliable electriccontacts between a current feeding element and travelling slide fastenerelements. To obviate this drawback, it has already been suggested to fixfastener stringers directly to the electric supply source at a pluralityof fastener elements before the oxidization commences; this, however,necessitates jigging which increases the manufacturing costs and impedescontinuous anodizing of slide fastener elements attached to carriertapes of consider- .able arbitrary length.

If a plurality of metal articles, which are large as coinpared with aslide fastener element, are to be anodized, it may be easier to fix theindividual articles to the electric supply source, but the disadvantagestill exists that the oxide layer formed on such an article duringanodizing is liable to impair the conduction of electric currentbetween. a current feeding element and the articles, if the currentfeeding element is not fixed to the articles, while if the currentfeeding element is fixed to the articles a conimpeded.

2,739,931 Patented Mar. 271, 1956 It is an object of this invention toprovide an improved method of and means for anodizing metal articles.

It is a more specific object of the invention to provide an improvedmethod of and means for anodizing fastener elements of slide fasteners.-

It is another object of the invention to provide an improved method ofand means for anodizing fastener elements on slide fastener tapes ofconsiderable arbitrary lengths.

It is a further object of the invention to provide an improved method ofand means for anodizing interlocked fastener elements of pairs of slidefastener tapes of considerable arbitrary lengths.

It is a more specific object of the invention, when anodizing metalarticles, to overcome difficulties resulting from the poorelectricconductivity of the oxide layers formed on such articles.

it is still another object of the invention to provide means foranodizing fastener elements on slide fastener tapes of considerableartitrary lengths while the tapes continuously travel from an input sideto an output side of an anodic bath.

It is still a further object of the invention to provide means forgradually increasing the intensity of the electric current flowingthrough each fastener element on a slide fastener tape While the tapecontinuously travels from an input side to an output side of an anodicbath.

It is yet another object of the invention to provide methods of andmeans for reliably anodizing fastener elements of slide fastener tapeswithout the necessity of jigging the elements to an electric supplysource.

These and other objects and advantages of the inventionwill becomeapparent to those skilled in the art from the following detaileddescription of the invention when read with reference to theaccompanying drawings, in which:

Fig. l somewhat diagrammatically illustrates a portion of two tapes towhich slide fastener elements are attached;

Fig. 2 is a section through a tape of Fig. 1;

Fig. 3 is a general perspective view of an arrangement of the invention,some parts being broken away;

Fig. 4 is a perspective View of a part of the arrangement of Fig. 3 on alarger scale;

Fig. 5 is a section along the line V-V of Fig. 4;

Fig. 6 illustrates a modification of a detail of Fig. 5; and

Fig. 7 illustrates another modification of the detail of Fig. 5.

The invention consists broadly in a method of anodizing a metal article,comprising the steps of immersing the article or a part thereof in asuitable anodic bath of an electrolytic cell, anodizing the article orits part while immersed in the anodic bath, scraping the oxide layerformed on thearticle from a portion thereof whereby to provide asufficiently good electric conduction through such portion, and feedingan electric current to the article through the scraped portion thereof.

electrically interconnected slide fastener elements attached to acarrier tape, comprising the steps of immersing adjacent fastenerelements of the tape in a suitable anodic bath of an electrolytic cell,anodizing the adjacent fastener elements, scraping the'oxide layerformed on said fastener elements from portions thereof, and feeding anelectric current through the scraped portions thereof. Preferably, theoxide layer is scraped from fastener element portions which lie at oneand the same side of the tape, while the oxide layer of fastener elementportions lying at the other side of the tape is not substantiallyinterfered with.

The invention also consists in a method of anodizing electricallyinterconnected fastener elements attached to a carrier tape, comprisingthe steps ofimmersing the tape or 'a' section thereof in a suitableanodic bathof an electroly-tic cell to anodize fastener elements of thetape or of the said tape section, removing the tape or the tape sectionfrom the anodic bath, scraping the oxide layer formed-on the fastenerelements while the 'tape or'the tape section wasim'mersed in the anodicbath from fastener element portions lying at one side of the tape,immersing the tape or the tape section again'in the anodic bath tocontinue the anodizingof the fastenerelements, removing the-tape or thetape section again from the anodic bath, scraping the oxide layer formedon the fastener elements while the tape or the tape section was immersedin the anodic bath from the fastener element portions lying at thesameone side of the tape as before, and, if necessary, continuing thisprocess until an oxide layer of sufiicient thickness has beenformedonthe fas tener element portions'lying'at the other side of the tape.

Preferably, fastener elements of two tapes are interlocked with eachother before the tapes or sections thereof are immersed in the anodicbath, whereby to 'treat the fastener element of the twotapes or thesections thereof simultaneously.

In any case, after the termination of the scraping process, or of thelast scraping process, the anodizing process may be continued, wherebysuperficially to anodize the previously scraped portion or portions.

It will be recognized that, by repeatedly scraping the oxide layer fromone and the samefastener element'portions, the oxide layer may be whollyor in part broken and/ or removed from the said-portions lying at oneside of the tape which therefore afford a good electric conductionthrough such portions of fastener elements and enable gradually tobuildup a substantially uniform oxide layer on the fastener elementportions lying at the other side of the tape, which advantageously formsthe visible front of the completed slide fastener, While the said oneside of the tape forms the rear of the slide fastener and is, thus,inmost cases not visible in use. Moreover, experience has shown that inmany cases, particularlyif the anodizing process is continued after thescraping process has been terminated, the effect of the scraping is not,or is hardly, visible to the naked eye.

The invention also consists in an arrangement for performing the methodshereinbefore described, comprising means for feeding a carrier tape towhich slide fastener elements are attached in a zig zag path through anelectrolytic cell, and means for scraping fastener element portionslying atone side of the'tape. The feeding means may be arrangedrelatively to the electrolytic cell in such a manner that each'part ofthe tape while travelling along the zigzag path is alternately immersedin an anodic bath of the electrolytic cell and removed therefrom, thescrap ing means being arranged for scraping fastener element portionswhile the tape part carrying the fastener ele ments which are beingscraped is removed from the anodic bath.

The scraping means may be rotatable brushes, for example Wire brushes,or knurled rollers.

Referring now to the drawings, Figs. 1 and 2 illustrate portions oftapes 1 having thickened edges 2 to which slide fastener elements 3 areattached. The tapes 1 are of a considerable arbitrary length, and thefastener elements 3 are spaced along the tapes 1 in groups separated onefrom the next by tape lengths a free from fastener elements 3. Eachthickened tape edge 2 comprises a plurality of metal wires 4 which areso arranged that the fastener elements 3 make mechanical and electriccontact With'the metal wires 4 whereby the fastener elements 3 areelectrically interconnected with one another. For cl-aritys sake, theWires 4 are illustrated as simply placed on top of the thickened edge 2and held in position'by the fastener elements 3 when clamped on to thetape edges. ln 'actual practice however, the wires are preferablyconnected to the tape edges 2 in any suitable manner.

The arrangement illustrated in Figs. 3 to 5 serves for anodizing thefastener elements 3 of the tapes 1. The arrangement comprises anelectrolytic cell formed by a metal tank 10 containing, in'use, asuitable anodic bath 11. A plurality of metallic guide rollers 12 arerota-tably mounted in brackets 13 and 14 of insulating material. Theends of the guide rollers 12 protrude beyond the bracket 14. Gear wheels15 are keyed to the protruding ends of the guide rollers 12, one toeach. Eachpair of adjacent gear wheels '15 mesh with an idling gearWheel 16. Furthermore, each gear Wheel 15 (except the first gear Wheel15 nearest the input side of the anodic bath at the extreme lefthandside of Fig. 3) meshes with a pinion 17 of smaller diameter, thepinions'17 being keyed to ends, protruding beyond the bracket 14, ofrollers 20 rotatably mounted in the brackets 13 and 14, one pinion 17being keyed to each roller 20. Each roller '20'has five guide grooves,the bottoms of the guide grooves being knurled as indicated in Fig. 4 at20a, the grooves being laterally defined by six raised portions 20b ofeach knurled roller 20. The Width of'one of the guide grooves formedbetween adjacentraised portions 20]) corresponds substantially-to thewidth of a pair of tapes 1 carrying interlocked fastener elements 3. Anelectric motor 21 drives the last guide roller '12 nearest the outputside of the 'ano dic bath (the extreme guide roller at the righthandside of Fig. 3) by means of a pulley 22, a pulley 23 and a belt 24, thepulley 22 being fixed to the rotor of the electric motor '21,and thepulley 23 to the said last guide roller '12. A wringer 25 is arranged atthe output side of the anodic 'bath and is driven by the electric motor21 by means of the pulley 20, a pulley 26 keyed to one of the pressrollers of the wringer 25 and abelt 27. In frames 30, guides 31 aremounted which are illustrated as rotatable idling rollers. Each metallicguide roller 12 is provided with a slip ring 32 electrically connectedin any known manner to the positive terminal of an electric supplysource, the negative terminal of which is connected at 33 to themetaltank 10 acting as the cathode-of the electrolytic cell. Electricresistors 34, 35, 36 are inserted in the electric connections betweenthe first three rollers 1'2 adjacent the input side of the anodic bathand the positive terminal of the electric supply source. The resistanceof the resistor 34 is higher than that'of the-resistor 35, which in'turnis higher than that of the resistor 3 6.

The arrangement operates as follows:

Five pairs of tapes 1 with their fastener-elements 3 interlocked are.passed substantially parallel to each other in a zig-zag path around thefirst guide roller 12 at the input side of, and arranged above,-theanodic bath 11, then down'and around the first guide 31 (counted fromthe left-hand side of Fig. 1) within the anodic bath 11, up andalong'one of the guide channels of the first knurled roller'20 above theanodic bath, around the second'guide roller 12, down and around thesecond guide 31 within the anodic bath, up and along the correspondingguide groove-of the second knurled roller 20, around the third guideroller .12, and so on,-until the last guide roller 12 has been reached,whereupon the tapes are threaded through the wringer 25. A suitableelectric potential is now applied to the electrolytic cell, and theelectric motor 21 is started. An electric current flows from thepositive potential of the supply source through all theguide rollers 12to thefastener elements of the tapes into the anodic bath and back tothe negative terminal of the electric supply source. The electric motor21 drives the wringer25 and the last guide roller 12 adjacent the outputside of theanodicbath. The gear wheel 15 keyed to the said last guideroller 12 drives the idling gear wheel 16 'meshingwith it, the idlinggear wheel 16 driving in turn the next gear wheel 15'and so on, wherebyall the guide rollers 12 are'driven in the same sense as indicated bythe inscribed arrows, the gear wheels 15 and 16 being so dimensionedthat all the guide rollers 12 rotate with a substantially equal speed.Each gear wheel 15 (except the first gear wheel at the input side of theanodic bath) drives one of the pinions 17 keyed to the knurled rollers20. As can be seen from Fig. 4, the knurled rollers 20 rotate in a senseopposite to the sense of rotation of the guide rollers 12. Since thediameter of each pinion is smaller than that of the gear wheels 15, theknurled rollers 20 rotate with a higher speed than the guide rollers 12.The rotation of the guide rollers 12 and the press rollers of thewringer causes the tapes 1 to travel through the anodic bath in azig-zag path from its input side to its output side in the direction ofthe arrow A in Fig. 1.

It will easily be seen that by such an arrangement when using a suitablespeed of travel for the tapes 1 and fastener elements 3 attached theretoit may be achieved that the fastener elements 3 are immersed in theanodic bath for short successive periods during each of which only athin oxide layer is formed which can easily be removed by the knurledrollers 20 scraping the adjacent sides of the fastener elements 3, whileowing to the repeated immersions the surfaces of the fastener elementswhich are not scraped by the knurled rollers 20 and which do not contactthe guide rollers 12 are provided with a uniform, sufiiciently thick,oxide layer when thefastener elements 3 emerge from the anodic bath atits output side. Moreover, if many, for example twelve, guide rollers 12are provided outside the electrolytic bath 11, the length of the tapes 1between successive guide rollers 12 may be kept short, whereby therequirements on the contacts between interlocked fastener elements 3 maybe reduced.

It is known that it is advantageous to increase gradually the currentthrough a metal article while anodizing it. Now, the resistors 34, and36 enable the electric current flowing from the respective guide rollers12 into the contacting fastener elements 3 to be kept smaller than thecorresponding currents flowing into contacting fastener elements 3 fromguide rollers 12 not associated with such resistors. The differentresistances of the said resistors cause the current through a certainfastener element 3 to increase gradually while the fastener elementtravels through the electrolytic bath 11, until a high current intensityis reached when the said fastener element contacts the fourth andfollowingguide rollers 12.

It will also be appreciated that it is no longer necessary for the wires4 to carry an anodizing current through the entire length of the tapeportions immersed at any instant of time in the anodic bath. With thearrangement described it is only required that the wires 4 carry thecurrent through the comparatively small length of the tape portionsbetween adjacent guide rollers 12 since at each such guide roller 12 anelectric connection with the supply source is established orre-established, while after the first guide roller 12 has been passed bya fastener element 3, the oxide layer on the fastener element 3 isscraped by. the knurled rollers 21} immediately before the said elementreaches one of the subsequent guide rollers 12. From the drawings itwill also be recognized that the knurled rollers 29 act all on one andthe same sides of the fastener elements.

It is somewhat difficult in practice to ascertain with certainty.whether the knurled rollers 20 in fact remove the oxide layer or onlybreak it up. Whatever, from a scientific point of view, the trueexplanation may be, it has been found that with the specific embodimentdescribed having twelve guide rollers outside the anodic bath, twelvefurther guides in the anodic bath and knurled rollers rotated at a highspeed, the guide rollers being electrically connected to a terminal ofthe electric supply source, a satisfactory anodizing was obtained of thesurfaces, remote from the guide rollers, of the fastener elements 3carried on the tapes 1 having wires 4 at their thickened edges 2 incontact with the fastener elements. The wringer 25 serves in knownmanner to remove liquid electrolyte from the tapes which maysubsequently be 6 washed and dyed together with the anodized fastenerelements in known manner.

Many modifications are possible. For example, less or more than fivepairs of tapes may be treated simultaneously. ments of which areinterlocked, single tapes may betreated. If pairs of tapes withinterlocked fastener elernentsare' treated, then in some cases theelectric direct connection between one fastener element of one tape andan adjacent interlocked fastener element of the other tape may besufiicient for allowing the electric anodizing current to flow, in whichcase the wires 4 may be dispensed with or may be only provided forbridging the tape lengths a between adjacent; groups of fastenerelements 3. The direct current electric supply source may be replaced byan alternating electric current supply source, in which case theresistors 34, 35, 36 may be replaced by electric impedances such aschoke coils.

In Fig. 6, reference numeral indicates a knurled roller similar to theknurled roller 20. However, the knurled roller 121) is so arranged thatit not only scrapes fastener elements of the tape 1 but also scrapes theperiphery of the adjacent guide roller 12 to keep the same clean.Moreover, an idling counter-roller 37, which preferably is made of anelastic material, presses the tapes 1 firmly against the respectiveguide roller 12 whereby to improve the electric contact between theguide roller 12 and the fastener elements of the tapes 1.

In the further modification of Fig. 7, the knurled roller is replaced bya rotating brush 220, which may be a wire brush, for scraping thefastener elements of the tapes 1 and also for cleaning the respectiveguide roller 12.

Other modifications are possible. For example, less or more than twelveguide rollers 12 and a corresponding number of knurled rollers 20 andguides 31 may be provided. The knurled rollers 20 need not be metallicrollers.

It should be clearly understood that the embodiments illustrated aregiven by way of example. Many further modifications, additions andomissions may be effected Without departing from the scope and spirit ofthe invention.

.I claim:

1. An arrangement for anodizing electrically interconnected fastenerelements attached to a carrier tape, com-- prising an electrolytic cellfor receiving an anodic bath, the electrolytic cell having an input sideand an output side, a rotatable guide roller arranged near the outputside of the electrolytic cell, a plurality of further rotatable guiderollers arranged between the said first mentioned guide roller and theinput side of the electrolytic cell, a plurality of guides, the saidguides and guide rollers being staggered relatively to one another, adrive for rotating at least the said guide roller at the output side ofthe electrolytic cell so that the tape when trained around the saidguide rollers and the said guides is drawn by the driven guide roller totravel around the said guide rollers and the said guides along asubstantial zig-zag path from the input side to the output side of theelectrolytic cell, and means for scraping fastener element portionslying at one side of the travelling tape.

2. An arrangement as claimed in claim 1, wherein the guide rollers arearranged to lie out-side the anodic bath of the electrolytic cell andthe guides are arranged to lie inside the said anodic bath so that thetape when travelling along the zig-zag path is in part immersed in, andin part removed from, the anodic bath.

3. An arrangement as claimed in claim 1, wherein gear means are providedbetween adjacent guide rollers, whereby positively to rotate all theguide rollers for drawing the tape or tapes through the anodic bath.

4. An arrangement as claimed in claim 1, wherein mean-s are provided forrotating the scraping means in the sense opposed to the direction oftravel of the fastener elements.

Instead of treating pairs of tapes the fastener ele-' 5.-'An'arrangement as claimed in claim 1,- wherein the guide rollersoutside the anodic bath are metal rollers, means being providedforelectrically connecting the metal rollers 'to a terminal of an electricsupply source, and further means being provided for electricallyconnecting theother terminal of the supply source to the anodic bathwhen in the electrolytic cell, whereby the fastener elements while inmechanical contact with the said guide rollers are connected through thesame to the said first terminal of the electric supply source. I V p 6.An arrangement as claimed in claim 5, wherein the means for electricallyconnecting at least one of the metal rollers to the terminal of theelectric supply source comprises an electric impedance for reducing theelectric current flowing through the said connecting means.

7. An arrangement as claimed in claim 5, wherein means are Provided foracting on the circumferences of the second and following guide rollers(counted from the input side of the electrolytic cell) for cleaning thesaid circumferences while in use. I

8. An arrangement as claimed in claim 5, wherein a counter-roller isprovided for pressing the tape while travelling around one of the guiderollers firmly against the same.

9. A method of anodizing fastener elements which are electricallyinterconnected and are attached to a fastener tape, comprising the stepsof continuously drawing at least a section of the said tape over a firstelectric contact element in such a manner that the said first contactelement successively makes electric contact with each of the fastenerelements, to feed an electric current to the interconnected fastenerelements, passing the tape section into an anodic bath to anodizefastener elements of the said tape section, removing the tape sectionfrom the anodic bath, scraping the oxide layer formed on a part, lyingat one side only of the tape, of each fastener element wherebysubstantially to restore the electric conductivity of the said parts,drawing the tape section over a second electric contact element in sucha manner that the said second contact element successively makeselectric contact with the scraped parts of the fastener elements tocontinue the feed of the electric current to the interconnected fastenerelements, passing the tape section of cyclically removing the tapesection'frorn the anodic bath,' scraping the oxide layer formed on thesaid parts, passing the tape section over an anode contact element andpassing the tape section into the anodic bath until an oxide layer ofsufficicnt thick'ness'has been built up on the remainder of eachfastener element of the tape section.

10. A method as claimed in claim 9, wherein fastener elements of twotapes are interlocked with each other before the tape sections are firstimmersed in the anodic bath, whereby to treat the fastener elements ofthe two tape sections simultaneously. M

ll. A'method as claimed in claim 9, wherein after the termination of thelast scraping process, the anodizing process is continued, wherebysuperficially to anodize the previously scraped portions.

12. A method of anodizing metal articles which. are electricallyinterconnected and attached to a flexible carrier, comprising the stepsof continuously drawing the articles into and through an anodic bath,drawing the articles over a plurality of spaced electric contactelements in such a manner that each contact element successively makeselectric contact with the same part of each article, passing an electriccurrent from a first of the said contact elements through a contactingarticle to other articles and thence through the anodic bath to acathode thereby frorning oxide layers on at least some of the articles,in the bath, scraping the oxide layer formed on the said article partswhereby to improve the electric conductivity of the said article parts,passing an electric current from 8 a second of the said contact elementsthrough a scraped contactingjarticle part to other articles and'thencethrough the anodic bathto the said cathode thereby forming an oxidelayer on each of the said articles in the bath, scraping the oxide layerformed at thesaid article parts, and

cyclically repeating the steps of passing an electric current, formin'gan oxide layer on articles in the bath, and scraping the oxide layerformed at the: said article part, until an oxide coating of a desiredthickness has been built up on the remainder of each article.

13 A method of anodizing fastener elements which are electricallyinterconnected and attached to, a fastener tape, comprising the steps ofcontinuously drawing the tape into and through an anodicbath across aplurality of spaced contact elements in such a manner that each contactelement successively makes electric contact with a part, lying at oneside only of the tape, of each of the said fastener elements, passing anelectric current from a first of the said contact elementsthroughacontacting fastener element to other fastener elements andthence through the anodic bath to a cathode thereby forming an oxidelayer on fastener elements, in the bath, scraping the oxide layerformedon the said parts of the fastener elements in the bath whereby toimprove the electric con ductivity of the said parts, passing anelectric current from a second of the said contact elements through thescraped parts of a contacting fastener element to other fastenerelements and thence through the anodic bath to the cathode therebyforming an oxide layer on each of the said fastener elements in thebath, scraping the oxide layer formed at the said part of each fastenerelement, and cyclically repeating the steps of passing an electriccurrent, forming oxide layers on fastener elements in the bath, andscraping the said part of each fastener element, until an oxide coatingof a desired thickness has been built up on the remaining part of eachfastener element.

14. An arrangement for anodizing fastener elements which areelectrically interconnected and attached to a carrier tape, comprisingan electrolytic cell for receiving an anodic bath and having an inputand output side, a first electric contact element, a first combinationof an electric contact element and a scraping means spaced from the saidfirst electric contact element, and atleast one further combination ofan electric contact element and a scrapingmeans spaced from theimmediately preceding combination, and means for continuously drawingthe carrier tape through. theelectrolyticv cell along an open path fromthe said input side to the said output side in such a manner that duringmovement of the can rier tape each fastener elementsuccessivelycontacts, the, first electric contactelement and during movement of thecarrier tape between the input and output side of the electrolytic cella part lying at one side only ofthecarrier tape of each of the saidfastener elements successively contacts the scraping meansandimmediately there afterthe electric contact element of eachcombination, so that the scraping means scrape the said element part andthe electric contact element contacts the scraped element part.

15. An arrangement as claimed inclaim 14, wherein the scraping means arerotatable brushes. 1 16. An arrangement as claimed in claim 15, whereinthe rotatable brushes are wire brushes.

17, An arrangement as claimed in claim 14, wherein the scraping meansare knurled rollers.

References Cited in the file of this patent UNITED STATES PATENTS 938,451 Aylsworth Oct. 26,

1. AN ARRANGEMENT FOR ANODIZING ELECTRICALLY INTERCONNECTED FASTENERELEMENTS ATTACHED TO A CARRIER TAPE, COMPRISING AN ELECTROLYTIC CELL FORRECEIVING AN ANODIC BATH THE ELECTROLYTIC CELL HAVING AN INPUT SIDE ANDAN OUTPUT SIDE, A ROTATABLE GUIDE ROLLER ARRANGED NEAR THE OUTPUT SIDEOF THE ELECTROLYTIC CELL, A PLURALITY OF FURTHER ROTATABLE GUIDE ROLLERSARRANGED BETWEEN THE SAID FIRST MENTIONED GUIDE ROLLER AND THE INPUTSIDE OF THE ELECTROLYTIC CELL, A PLURALITY OF GUIDES, THE SAID GUIDESAND GUIDE ROLLERS BEING STAGGERED RELATIVELY TO ONE ANOTHER, A DRIVE FORROTAT-